ASoC: dt-bindings: renesas,rsnd.yaml: tidyup reg/reg-name

Tidyup reg/reg-name "maxItems".
Pointed by Krzysztof, and corrected by Rob.

Link: https://lore.kernel.org/r/46974ae7-5f7f-8fc1-4ea8-fe77b58f5bfb@linaro.org
Link: https://lore.kernel.org/r/20230207211621.GA4158591-robh@kernel.org


Reported-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/87pmalt01x.wl-kuninori.morimoto.gx@renesas.com


Signed-off-by: Mark Brown <broonie@kernel.org>